An assault on the city’s Landmarks Law has quietly been taking place in the corridors of power, through press releases and legislation, for going on a year now. But groups allied against landmarking are planning to fire their first public volley tomorrow, The Observer has learned, with the announcement of a coalition of development and labor groups known as the Responsible Landmarks Coalition.

Formed by the Real Estate Board of New York, it is made up of a number of influential real estate and labor organizations, “and it is only going to get bigger,” one person involved in the effort said. “We are going to have some very major institutions looking at these landmarks.”

The main issues of concern for the coalition are the increasing prevalence of historic districts, a lack of transparency in the landmarking process, and insufficient public input. The coalition will argue that the growing number of landmark buildings and historic districts are hampering the city’s economy and stymieing development.

“We’re concerned that if you apply the concept of landmarks preservation too much, you resrtrict housing and impinge on other aspects of city life,” said Richard Anderson, president of the New York City Building Congress, a trade group for architects, engineers and contractors.

In addition to the Building Congress and the Real Estate Board, the coalition also include the Manhattan Chamber of Commerce; three residential landlord groups: the Rent Stabilization Association, the Council of New York Cooperatives and Condominiums, the Community Housing Improvement Program; the building workers union 32BJ; and two groups representing construction unions, the Building Trades Employers Association and the Building and Construction Trades Council.

In addition to drafting a three page signatory letter that is part policy document, part manifesto, the group has launched a new site, responsible-landmarks-coalition.org, as well as Facebook and Twitter accounts to drive their message. The Facebook page already has three “likes.”

Clearly illustrating the group’s point is a slideshow on the site of eight projects, in four pairs, with the words “The Landmarks Law is BROKEN when these are both landmarks.” On the right are rows of townhouses, the Chrsysler Building, the Dakota, on the left an auto body shop and a faceless industrial building.

The group insists it supports the idea of landmarking buildings.

“New York City is known for its great landmarks, which help define our city and drive our economy,” REBNY president Steven Spinola said in a statement, but he charges that “overzealous landmarking” of gas stations and the like makes development in the city prohibitively costly.

This underscores a particular concern with historic districts, one of two designations the Landmarks Preservation Commission can award. By naming an individual landmark, the commission says this specific building has merit. But in creating a far-reaching historic district, like those in Soho or Brooklyn Heights, elevates unspectacular buildings beyond their worth.

This is a somewhat disingenuous argument, since that gas station can indeed be developed, but whatever is planned there must be approved by the commission. This adds to the cost and the time spent developing the project, but it also ensures continuity with the surrounding neighborhood—Soho will still look like Soho, the Upper East Side, the Upper West Side, and not the two mixed up together.

Elisabeth de Bourbon, a spokeswoman for the Landmarks Preservation Commission, declined to comment on a pending announcement.

It was two recent districts, on West End Avenue on the Upper West Side and the Downtown Brooklyn Skyscraper District that have particularly inflamed the groups, who argue that the opportunities to build new and maintain old buildings in these neighborhoods, as well as other districts, have been greatly hampered. There is also the question finding out from the commission where in the landmarking process a building is. The group wants guidelines for buildings enumerated when a building is landmarked, giving the owners more certainty about what can be built in the future.

Supporters of the commission argue that the complaints about preservation are overblown. Peg Breen is president of the Landmarks Conservancy, a group that provides funding for renovation work on landmarks, and she said that her group did an informal survey of many of the group’s loan recipients, many of whom said they did not feel owning a landmark had increased their costs. “If you have to fix a roof, you have to fix a roof,” she said.

Furthermore, Ms. Breen pointed to numerous studies that find preservation increases or maintains property values (partly because of supply and demand issues) as an argument for its value. “Preservation is jobs, too,” she said. And with only 4 percent of the city protected by the Landmarks law, “that leaves plenty of room for everybody else.”

Nevermind the fact that landmarking does not prohibit development, but simply regulates it. “That is the problem, though,” Mr. Anderson said. “New York is the most expensive city in the country to build in, and regulation is a big part of that, of which landmarks is a big part.” With more than 12 percent of Manhattan under preservation protection, as well as large swathes of Brownstone Brooklyn, it can be harder to build whatever you want.